Help! Is this something bad?

I was watching the girls and I saw one open her beak really wide. She did this repeatedly for a bit. I answered the phone and when I went back to look, she wasn't doing it and was running around the yard with the others. Is this normal? Was she yawning or something. My instinct tells me she's fine since she is acting normal. I held her and other than being skinny (like they all are), she felt okay.

Could have been something tickling her throat, or something temporarily stuck. I see an occasional bird do similar things, but it's not very often. (Different birds, days or weeks apart, etc.). If they are skinny, you might want to check if they need worming or have any mites or lice.

They HAD worms. I wormed them with Wazine 4 weeks ago and Ivermectin 2 weeks ago. I'm hoping they start to fatten up. All look healthy with alert eyes, clear nose, shiny feather, etc and all are very active with good appetites. Hopefully they chunk up a bit soon. Not fat, but just more meat on their bones.